/* cnf.c: read config files.

   Copyright 1994, 1995, 1996, 1997, 2008, 2009, 2011, 2012, 2016 Karl Berry.
   Copyright 1997-2005 Olaf Weber.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this library; if not, see <http://www.gnu.org/licenses/>.  */

#include <kpathsea/config.h>
#include <kpathsea/c-fopen.h>
#include <kpathsea/c-ctype.h>
#include <kpathsea/c-pathch.h>
#include <kpathsea/cnf.h>
#include <kpathsea/db.h>
#include <kpathsea/hash.h>
#include <kpathsea/line.h>
#include <kpathsea/paths.h>
#include <kpathsea/pathsearch.h>
#include <kpathsea/tex-file.h>
#include <kpathsea/variable.h>

/* By using our own hash table, instead of the environment, we
   complicate variable expansion (because we have to look in two
   places), but we don't bang so much on the system.  DOS and System V
   have very limited environment space.  Also, this way
   `kpse_init_format' can distinguish between values originating from
   the cnf file and ones from environment variables, which can be useful
   for users trying to figure out what's going on.  */

#define CNF_HASH_SIZE 751
#define CNF_NAME "texmf.cnf"


/* Do a single line in a cnf file: if it's blank or a comment or
   erroneous, skip it.  Otherwise, parse
     <variable>[.<program>] [=] <value>
   Do this even if the <variable> is already set in the environment,
   since the envvalue might contain a trailing :, in which case we'll be
   looking for the cnf value.
   
   We return NULL if ok, an error string otherwise.  */

static string
do_line (kpathsea kpse, string line)
{
  unsigned len;
  string start;
  string value, var;
  string prog = NULL;

  /* Skip leading whitespace.  */
  while (*line && ISSPACE (*line))
    line++;

  /* More to do only if we have non-comment material left.  */
  if (*line == 0 || *line == '%' || *line == '#')
    return NULL;

  /* Remove trailing comment: a % or # preceded by whitespace.  Also
     remove any whitespace before that.  For example, the value for
       foo = a#b  %something
     is a#b.  */
  value = line + strlen (line) - 1; /* start at end of line */
  while (value > line) {            
    if (*value == '%' || *value == '#') {
      value--;                      /* move before comment char */
      while (ISSPACE (*value))
        *value-- = 0;               /* wipe out as much preceding whitespace
      continue;                        (and comment) as we find */
    }
    value--;                        /* move before the new null byte */
  }

  /* The variable name is everything up to the next space or = or `.'.  */
  start = line;
  while (*line && !ISSPACE (*line) && *line != '=' && *line != '.')
    line++;

  /* `line' is now one character past the end of the variable name.  */
  len = line - start;
  if (len == 0) {
    return ("No cnf variable name");
  }
  
  var = (string) xmalloc (len + 1);
  strncpy (var, start, len);
  var[len] = 0;

  /* If the variable is qualified with a program name, find out which. */
  while (*line && ISSPACE (*line))
    line++;
  if (*line == '.') {
    /* Skip spaces, then everything up to the next space or =.  */
    line++;
    while (ISSPACE (*line))
      line++;
    start = line;
    while (!ISSPACE (*line) && *line != '=')
      line++;

    /* It's annoying to repeat all this, but making a tokenizing
       subroutine would be just as long and annoying.  */
    len = line - start;
    prog = (string) xmalloc (len + 1);
    strncpy (prog, start, len);
    prog[len] = 0;
  }

  /* Skip whitespace, an optional =, more whitespace.  */
  while (*line && ISSPACE (*line))
    line++;
  if (*line == '=') {
    line++;
    while (*line && ISSPACE (*line))
      line++;
  }

  /* The value is whatever remains.  Remove trailing whitespace.  */
  start = line;
  len = strlen (start);
  while (len > 0 && ISSPACE (start[len - 1]))
    len--;
  if (len == 0) {
    return ("No cnf value");
  }
  
  value = (string) xmalloc (len + 1);
  strncpy (value, start, len);
  value[len] = 0;

  /* Suppose we want to write a single texmf.cnf that can be used under
     both NT and Unix.  This is feasible except for the path separators
     : on Unix, ; on NT.  We can't switch NT to allowing :'s, since :
     is the drive separator.  So we switch Unix to allowing ;'s.  On the
     other hand, we don't want to change IS_ENV_SEP and all the rest.

     So, simply translate all ;'s in the path
     values to :'s if we are a Unix binary.  (Fortunately we don't use ;
     in other kinds of texmf.cnf values.)  */

  if (IS_ENV_SEP(':')) {
      string loc;
      for (loc = value; *loc; loc++) {
          if (*loc == ';')
              *loc = ':';
      }
  }

  /* We want TEXINPUTS.prog to override plain TEXINPUTS.  The simplest
     way is to put both in the hash table (so we don't have to write
     hash_delete and hash_replace, and keep track of values' sources),
     and then look up the .prog version first in `kpse_cnf_get'.  */
  if (prog) {
    string lhs = concat3 (var, ".", prog);
    free (var);
    free (prog);
    var = lhs;
  }
  /* last-ditch debug */
  /* fprintf (stderr, "kpse/cnf.c hash_insert(%s,%s)\n", var, value); */
  hash_insert (&(kpse->cnf_hash), var, value);

  /* We should check that anything remaining is preceded by a comment
     character, but we don't.  Sorry.  */
  return NULL;
}

/* Read all the configuration files in the path.  */

static void
read_all_cnf (kpathsea kpse)
{
  string *cnf_files;
  string *cnf;
  const_string cnf_path = kpathsea_init_format (kpse, kpse_cnf_format);

  kpse->cnf_hash = hash_create (CNF_HASH_SIZE);

  cnf_files = kpathsea_all_path_search (kpse, cnf_path, CNF_NAME);
  if (cnf_files && *cnf_files) {
    for (cnf = cnf_files; *cnf; cnf++) {
      string line;
      string msg;
      unsigned lineno = 0;
      FILE *cnf_file = xfopen (*cnf, FOPEN_R_MODE);
      if (kpse->record_input)
        kpse->record_input (*cnf);

      while ((line = read_line (cnf_file)) != NULL) {
        unsigned len;
        lineno++;
        len = strlen (line);
        /* Strip trailing spaces. */
        while (len > 0 && ISSPACE(line[len-1])) {
          line[len - 1] = 0;
          --len;
        }
        /* Concatenate consecutive lines that end with \.  */
        while (len > 0 && line[len - 1] == '\\') {
          string next_line = read_line (cnf_file);
          lineno++;
          line[len - 1] = 0;
          if (!next_line) {
            WARNING2 ("%s:%d: (kpathsea) Last line of file ends with \\",
                       *cnf, lineno);
          } else {
            string new_line;
            new_line = concat (line, next_line);
            free (line);
            line = new_line;
            len = strlen (line);
          }
        }

        msg = do_line (kpse, line);
        if (msg) {
          WARNING4 ("%s:%d: (kpathsea) %s on line: %s",
                    *cnf, lineno, msg, line);
        }
        free (line);
      }

      xfclose (cnf_file, *cnf);
      free (*cnf);
    }
    free (cnf_files);
  } else {
    string warn = getenv ("KPATHSEA_WARNING");
    if (!(warn && STREQ (warn, "0"))) {
      WARNING1
  ("kpathsea: configuration file texmf.cnf not found in these directories: %s",
        cnf_path);
    }
  }
}

/* Read the cnf files on the first call.  Return the first value in the
   returned list -- this will be from the last-read cnf file.  */

const_string
kpathsea_cnf_get (kpathsea kpse, const_string name)
{
  string ctry;
  const_string ret, *ret_list;

  /* When we expand the compile-time value for DEFAULT_TEXMFCNF,
     we end up needing the value for TETEXDIR and other variables,
     so kpse_var_expand ends up calling us again.  No good.  Except this
     code is not sufficient, somehow the ls-R path needs to be
     computed when initializing the cnf path.  Better to ensure that the
     compile-time path does not contain variable references.  */
  if (kpse->doing_cnf_init)
    return NULL;

  if (kpse->cnf_hash.size == 0) {
    /* Read configuration files and initialize databases.  */
    kpse->doing_cnf_init = true;
    read_all_cnf (kpse);
    kpse->doing_cnf_init = false;

    /* Since `kpse_init_db' recursively calls us, we must call it from
       outside a `kpse_path_element' loop (namely, the one in
       `read_all_cnf' above): `kpse_path_element' is not reentrant.  */
    kpathsea_init_db (kpse);
  }

  /* First look up NAME.`kpse->program_name', then NAME.  */
  assert (kpse->program_name);
  ctry = concat3 (name, ".", kpse->program_name);
  ret_list = hash_lookup (kpse->cnf_hash, ctry);
  free (ctry);
  if (ret_list) {
    ret = *ret_list;
    free (ret_list);
  } else {
    ret_list = hash_lookup (kpse->cnf_hash, name);
    if (ret_list) {
      ret = *ret_list;
      free (ret_list);
    } else {
      ret = NULL;
    }
  }

  return ret;
}

#if defined(KPSE_COMPAT_API)
const_string
kpse_cnf_get (const_string name)
{
    return kpathsea_cnf_get(kpse_def, name);
}
#endif